1. Field of the Invention
The invention relates to a method and an arrangement for carrying out repair and/or maintenance work in the inner casing of a multishell turbomachine.
2. Discussion of Background
Depending on the pressure and temperature ratios to be expected, turbomachines are provided with single-shell or multishell casings. The requisite wall thickness of single-shell outer casings, in view of the thermal stresses, in particular at high pressures and temperatures, becomes relatively large. By the use of multishell casings, the effective pressure differences can be reduced and thus the wall and flange thicknesses can be reduced accordingly. In such multishell turbomachines, the inner casing carrying the blading is supported by the outer casing. In gas-turbine plants, such an inner casing may also accommodate the combustion chamber. As a result, the access required during repair and/or maintenance work to the various components arranged in the interior of the combustion chamber, such as, for example, the heat shields, the burners and their mountings, is not possible until after the opening of the outer casing and the subsequent opening of the combustion-chamber casing.
To avoid such time-consuming and costly measures in connection with the requisite repair and/or maintenance work, it is known to provide both the outer casing and the combustion-chamber casing of a gas-turbine plant with so-called manholes (see the article "Die Gasturbine GT13E2 ein richtungsweisendes Konzept fur die Zukunft" in ABB Technik Jun. 7, 1993, pages 11-16, FIG. 3). Through these manholes, either a fitter can get into the combustion chamber or another appropriately equipped tool carrier can be introduced. Of course, there must be sufficient space in the interior of the combustion chamber for this purpose, which is not always guaranteed. In addition, some extra design and constructional work is required in order to make a manhole in the combustion chamber in a functionally reliable manner, which results in at least increased total costs.